Infiltration and organic carbon pools under the long term use of farm yard manure and mineral fertilizer

Full Length Research Article Farmyard manure (D) in combination with inorganic fertilizer (NPK) trial was started at Samaru in 1950 to assess nutrient imbalances resulting from increasing use of mineral fertilizer on some poorly buffered soils as well as to improve and optimize productivity of these soils under intensive agricultural land use. Soil physical and chemical properties were studied in selected plots, with the aim of identifying treatment(s) that best improve soil quality over a longterm period. A total of ten treatments were evaluated namely: Inorganic fertilizer (NPK) in combination with farmyard manure (D), that is, (D+NPK), NPK only, D only, D + phosphorus (P), D + potassium (K), D + nitrogen (N), N only, K only, P only and a Control receiving neither NPK nor D. The results obtained show that long term application of manure with or without NPK increased aggregate stability and mean weight diameters (MWD) of the water stable aggregates for soils amended with D+P, D+K and NPK. Soils amended with D+P and D+NPK sequestered more total soil organic carbon than all other treatments. The soil organic carbon of aggregate fractions was very low. Higher soil bulk densities were observed for the no amendment (Control) plot, D+K, and NPK treated soils. However, the D+P, D+N and N treatments recorded a lower soil bulk density. Soils treated with D+P and NPK recorded higher infiltration rate than the control. Treatments with D only also generally had higher plant available water than the other treatments. Hence, on the basis of soil quality considered, the long term D+P treatment provides the most sustainable agricultural practice. ©2013 BluePen Journals Ltd. All rights reserved